Several patents have been allowed in the field of telephone controls and other remotely controlled devices.
The apparatuses or devices described in said patents have phone call trains detector systems that automatically attend to the called phone line, close the phone loop (thus establishing the d.c. current or conversation circuit) and utilize several successive coding and decoding stages to perform different functions through remote control.
Most of the apparatuses patented up to now, when automatically attending phone calls, emit a distinctive signal advising the calling party to send signals or codes which are in general of a restrictive or exclusive nature. This circumstance results in the fact that calling parties unfamiliar with those systems become upset when the automatic call attention takes place, preventing them from establishing a normal phone communication as they wished to do.
A similar frustration is suffered by calling parties any time their phone calls are attended (after being charged for) by an automatic call attention device announcing to them that they are in communication with a remotely controlled apparatus which can only be activated through the sending of codes unknown to the calling party. Of course, such a calling party has no other chance but to give up the phone call.
On the other hand, anybody wishing until now to install more than one automatic call attention phone device, can only couple one piece of equipment at a time to his phone line.
Likewise, it must be kept in mind that most owners of equipment activated by phone remote controls do not wish calling parties not having been previously informed by the owners to know that such an equipment is installed to the phone or how such equipment works.
The aim of this invention, --in its different variants--, is that of solving the aforementioned problems, allowing any calling party, --familiar or unfamiliar with the operation of equipments designed by phone remote controls, to be attended by equipments not offering the drawbacks mentioned in the foregoing paragraphs.